There has been known an apparatus including a loop buffer configured to store instruction operations (see Patent Document 1). The instruction operations are dispatched from the loop buffer responsive to detecting the apparatus is in a loop buffer mode. The apparatus further includes a loop buffer control unit coupled to the loop buffer. The loop buffer control unit tracks a distance from a start of a loop candidate containing a plurality of instructions to each “taken branch” within the loop candidate. Then, the loop buffer control unit initiates the loop buffer mode responsive to detecting distances from the start of the loop candidate to each of the “taken branches” are invariant for at least a given number of iterations of the loop candidate.
Further, there has been known a data processor in which an instruction read out from an instruction storage means is decoded by an instruction decoding means and an instruction executing means is controlled by control information output from the instruction decoding means (see Patent Document 2). A control means causes a control information storage means to hold control information obtainable as a result of decoding a series of instructions that should be executed repeatedly and causes the control information storage means to output the control information repeatedly in response to occurrence of an internal state where the series of instructions equivalent to the number equal to or less than a first upper limit value should be executed repeatedly. Additionally, the control means actually stops operations of the instruction storage means and the instruction decoding means.
Patent Document 1: Japanese Laid-open Patent Publication No. 2014-13565
Patent Document 2: Japanese Laid-open Patent Publication No. 09-114660
Patent Document 1 initiates the loop buffer mode responsive to detecting distances from the start of the loop candidate to each of the “taken branches” are invariant for at least a given number of iterations of the loop candidate. Patent Document 2 causes the control information storage means to hold the control information obtainable as a result of decoding a series of instructions that should be executed repeatedly and causes the control information storage means to output the control information repeatedly in response to occurrence of an internal state where the series of instructions equivalent to the number equal to or less than the first upper limit value should be executed repeatedly. Patent Documents 1 and 2 are to judge loop processing based on control information obtainable as a result of decoding instructions.